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Biomedical subjects

M Johannesson

Publications and source records attributed to M Johannesson.

140 records · Page 8Linked to original sources
PubMedDate not supplied

Health-related quality of life in patients with psoriasis and atopic dermatitis measured with SF-36, DLQI and a subjective measure of disease activity.

The impact of skin diseases on health-related quality of life is considerable. It is important to quantify the patient's perspective of the severity of their disease. Health-related quality of life was measured in 366 patients with skin diseases attending the dermatology outpatient clinic in Uppsala, Sweden, from November 1996 to December 1997, with 1 generic (SF-36) and 1 disease-specific (DLQI) health-related quality of life instrument, and a subjective measure of disease activity. The SF-36 mean scores were below those of the age- and gender-matched general population in Sweden. No difference in health-related quality of life was found between men and women or between patients with atopic dermatitis and psoriatic patients. However, patients with psoriatic arthritis had significantly poorer health-related quality of life than both patients with atopic dermatitis and psoriatic patients. The estimated correlations between the instruments were in the expected direction and mostly significant. The results confirm that skin diseases have an adverse impact on patients' health-related quality of life.

Adaptation, Psychological↗
PubMedDate not supplied

Are healthy-years equivalents an improvement over quality-adjusted life years?

The construct of the healthy-years equivalent (HYE) has been proposed as an alternative to the quality-adjusted life year (QALY) on the grounds that it avoids certain restrictive assumptions about preferences and also incorporates attitudes toward risk. The authors review the construct of the QALY, including both the commonly used risk-neutral formulation and the more general formulation that permits risk aversion (or risk preference) with respect to remaining life years. They show that the HYE adds flexibility to the risk-neutral form of the QALY by permitting the rate of tradeoff between life years and quality of life to depend on the life span, albeit at the cost of eliciting numerous additional time-tradeoff assessments. However, the claim that the HYE incorporates attitudes toward risk is incorrect, and the proposed two-stage procedure to measure HYEs is neither necessary nor sufficient to incorporate attitudes toward risk. In fact, the HYE assumes risk neutrality with respect to healthy years of life and, therefore, is less suitable for decisions under uncertainty than is the general (risk-averse) form of the QALY.

Cost of Illness↗
PubMedDate not supplied

A note on QALYs, time tradeoff, and discounting.

The theoretical model of QALYs is based on risk neutrality with respect to life years or constant proportional risk posture with respect to life years. It is shown that discounting of QALYs is inconsistent with these assumptions. For discounting to be consistent with individual preferences in a QALY model, individuals have to be risk-neutral with respect to discounted life years or exhibit constant proportional risk posture with respect to discounted life years. For the time-tradeoff method to be consistent with these assumptions, the QALY weights have to be derived by dividing the number of discounted life years in full health by the number of discounted life years in the assessed health states.

Age Factors↗
PubMedDate not supplied

The impact of age on the cost-effectiveness of hypertension treatment: an analysis of randomized drug trials.

The aim of this study was to investigate whether any consistent pattern exists with respect to the cost-effectiveness of hypertension treatment and age, based on the results of randomized drug trials. Data about age, entry diastolic blood pressure, and relative risks of coronary heart disease (CHD) and stroke from 19 randomized trials were used to derive point estimates of the cost-effectiveness of each trial. The relationship between age and cost per life-year gained was then estimated by regression analysis, controlling for entry diastolic blood pressure. The regression analysis shows a statistically significant average decrease in the cost per life-year gained of about SEK 15,000 per year of older age for both men and women ($1 = SEK 6). Sensitivity analysis showed that the improvement in cost-effectiveness with age was stable towards various assumptions, but that the magnitude of the improvement varied greatly with the discount rate. Based on the results of randomized drug trials, it is concluded that the cost-effectiveness of hypertension treatment improves with patient age for both men and women.

Adult↗
PubMedDate not supplied

Willingness to pay for reductions in angina pectoris attacks.

To compare the costs of health care programs, with the benefits, the values of changes in health status must be expressed in monetary terms. The development of methods to estimate willingness to pay for changes in health status is therefore of interest. This paper reports the results of a contingent valuation study measuring willingness to pay for reductions in angina pectoris attacks. An innovative study design allowed analysis on the data on willingness to pay using two approaches, a binary question and a bidding-game technique. Percentage reductions in anginal attacks were varied randomly in different subsamples, and data were collected about angina pectoris status, attack rate, and income to test the internal validity of the contingent valuation method. Willingness to pay for a 50% reduction in the attack rate for three months was estimated to be about SEK 2,500 ($345) with the binary approach, and about SEK 2,100 ($290) using the bidding-game technique. Regression analyses showed that income, angina pectoris status, attack rate, and percentage reduction in attack rate were all related to willingness to pay, in agreement with the authors' hypothesis.

Aged↗
PubMedDate not supplied

The validity of QALYs: an experimental test of constant proportional tradeoff and utility independence.

Pliskin, Shepard, and Weinstein identified three preference conditions that ensure that quality-adjusted life years (QALYs) represent preferences over gambles over chronic health profiles. This paper presents an experimental test of the descriptive validity of two of these preference assumptions: utility independence and constant proportional tradeoff. Eighty students at the Stockholm School of Economics and 92 students at Erasmus University Rotterdam participated in the experiment. The results of the experiment support the descriptive validity of constant proportional tradeoff: both within groups and between groups constant proportional tradeoff could not be rejected. The results are less supportive of the descriptive validity of utility independence. Within-groups utility independence was rejected. Between-groups utility independence could not be rejected, but this may have been due to a lack of statistical power. Analysis of the individual responses revealed that without adjustment for imprecision of preference, 39 respondents (22.8%) satisfied constant proportional tradeoff. Twenty-three respondents (13.4%) satisfied utility independence without adjustment for imprecision of preference. However, because of the relative unfamiliarity of the respondents with both the health states to be evaluated and the methods of health-state-utility measurement, it is likely that the respondents' preferences were imprecise. Adjusted for imprecision of preference, the upper estimates of the proportions of respondents who satisfied constant proportional tradeoff and utility independence, respectively, were 90.1% (155 respondents) and 75.6% (130 respondents). Pliskin et al. further derived that if an individual's preferences satisfy both constant proportional tradeoff and utility independence, then these preferences can be represented by a more general, risk-adjusted QALY model. Without adjustment for imprecision of preference, ten respondents (5.8%) satisfied both constant proportional tradeoff and utility independence. Adjusted for imprecision of preference, the upper estimate of the proportion of respondents who satisfied both constant proportional tradeoff and utility independence was 68.6% (118 respondents). The results of this study indicate that constant proportional tradeoff holds approximately. The evidence is much weaker for utility independence, however. This has important implications for the use of QALY-type measures in medical decision making.

Activities of Daily Living↗
PubMedDate not supplied

An experimental test of a theoretical foundation for rating-scale valuations.

A major advantage of using a rating scale in health-utility measurement is its practical applicability: the method is relatively easy to understand, and various health states can be assessed simultaneously. However, a theoretical foundation for rating-scale valuations has not been established. The primary aim of this paper is to present a theoretical foundation for rating-scale valuations based on the theory of measurable value functions and to provide a consistency test to see whether rating-scale valuations do indeed elicit a measurable value function. If rating-scale valuations elicit a measurable value function, then Dyer and Sarin have shown how they are related to von Neumann-Morgensterm (vNM) utilities. The appropriate technique to measure vNM utilities is the standard gamble. Torrance has suggested that rating-scale valuations and standard-gamble valuations are related by a power function. A secondary aim of this paper is to examine the relationship between rating-scale valuations and standard-gamble valuations hypothesized by Torrance. An experiment was designed to test consistency of rating-scale valuations and the relationship between rating-scale valuations and standard-gamble valuations. The experiment tested whether rating-scale valuations are independent of the context in which they are elicited, as they should be if they elicit points on a measurable value function. 80 Swedish and 92 Dutch respondents participated in the experiment. The results showed that rating-scale valuations depend on the number of preferred alternatives in the task and thus violate a basic property of measurable value functions. The estimation of the power function did not result in stable results: parameter estimates varied, in some cases there was indication of misspecification, and in most cases there was indication of heteroskedastic errors. The implications of these findings for the common use of rating-scale valuations in cost-utility analysis are serious: the dependency of the rating-scale valuations on the other health states included in the task casts serious doubts on the validity of the rating-scale method.

Activities of Daily Living↗
PubMedDate not supplied

Incorporating future costs in medical cost-effectiveness analysis: implications for the cost-effectiveness of the treatment of hypertension.

It has been shown that the difference between consumption and production during life years gained should be included as a cost in cost-effectiveness analysis. In this study the authors estimate the impact of including these future costs on the cost-effectiveness of the treatment of hypertension in Sweden. The cost per quality-adjusted life year (QALY) gained changes little among young men and women due to the addition of future costs, but increases by about $14,000 for middle-aged men and women and about $27,000 for older men and women. When future costs are not included, the cost per QALY gained is generally lowest among older men and women, but when future costs are included, the cost per QALY gained is generally lowest among middle-aged men and women. The authors conclude that the total resource consequences of changes in mortality should be routinely considered in cost-effectiveness analyses.

Adult↗
PubMedDate not supplied

The relationship between health-state utilities and the SF-12 in a general population.

It would be a major advance if quality-of-life instruments could be translated into health-state utilities. The aim with this study was to investigate the relationship between the SF-12 and health-state utilities, based on responses to a postal questionnaire sent to a random sample of 8,000 inhabitants, aged 20-84 years, in the general population. The questionnaire included the SF-12, a rating-scale (RS) question, and a time-tradeoff (TTO) question; the response rate was 68%. Age, gender, and the 12 items of the SF-12 were used as explanatory variables in a linear regression analysis of the health-state utilities. The regression models explained about 50% of the variance in the RS answers and about 25% of the variance in the TTO answers. Most of the SF-12 items were related to the health-state utilities in the expected ways, with especially strong results for the RS method. The results suggest that the SF-12 can be converted to health-state utilities, but that further work is needed to reliably estimate the conversion function.

Activities of Daily Living↗
PubMedDate not supplied

Inconsistencies in the "societal perspective" on costs of the Panel on Cost-Effectiveness in Health and Medicine.

A key recommendation of the recent Panel on Cost-Effectiveness in Health and Medicine was that cost-effectiveness analyses be carried out from a societal perspective. The authors show that two of the Panel's recommendations concerning costs are not consistent with a societal perspective, and how to correct those inconsistencies. In its recommendations concerning costs resulting from morbidity, the Panel advises excluding lost income from costs in the belief that individuals take income changes into account when they respond to the quality-of-life questions that are used to calculate quality-adjusted life years (QALYs). It is shown that even if individuals do consider income changes in responding to these quality-of-life questions, this recommendation would seriously underestimate production losses due to morbidity, since individuals do not bear a major part of lost production. In its recommendations concerning costs resulting from mortality, the Panel does not require that health care costs for "unrelated" illness and non-health care consumption and production during added life years be included in the Reference Case. It is shown that omitting these costs will seriously distort comparisons of programs at different ages and favor programs that extend life over those that improve quality of life. This can be corrected by including total consumption minus production in added life-years among costs.

Cost of Illness↗
PubMedDate not supplied

A computer simulation model for cost-effectiveness analysis of cardiovascular disease prevention.

In this paper a computer simulation model for cost-effectiveness analysis of cardiovascular disease prevention is presented. Cost-effectiveness analysis makes it possible to compare the cost-effectiveness of different interventions in order to maximize the health effects for a given amount of resources. The computer simulation model was written in Turbo-Pascal to be used on an IBM-PC-compatible. The model was based on the 8-year logistic multivariate risk equations for CHD and stroke from the Framingham Heart Study, but the regression coefficients can easily be changed if local data exist. The main advantages with the model are that it is easy to use, transparent, and flexible. The model was mainly developed for scientific purposes, but should be useful also for educational purposes and clinical decision analysis. The modelling approach used should also be useful in many other medical areas.

Adult↗